I would like to know when I need to start worrying about CPU temps. I have my core OCed to 3.4ghz at the moment, minor I know but it puts out a little more heat than I want, and is usually idling at 45*C. I've got fantastic air flow in my case at the moment.

I've got two Scythe "Super Kaze" 120mm fans, one in the top front as intake and one at the back as exhaust, A single Silverstone 120mm Fan that pushes air directly on my 3 video cards, And I've got one 80mm fan that's pushing more air right on top of the CPU.

You should replace that other fan as an exhaust. Currently you are running a positive pressure case, which means your CPU temps will rise as you are not able to get air out as fast as you need. In a negative pressure case, more dust can come in, but you get lower component temps as heat is never in a fight to leave the case.

As for your temps, that idle temp is very high.

You should probably look into getting a better cooler before a case fan.

Idle at 45c ooOO.. you really need to get that chip cooler. Maybe a new cooler is in line. A mega or a xiggy dark knight should fix that. Also your air flow needs to be evened out, 3 intakes and one exaust.. you need more exaust and less intake.

You would get better temps with the stock cooler than the Arctic Cooler you are using. A good aftermarket cooler would be better. Like you I have a positive pressure case but my Xiggy can keep safe temps, even when my vcore is 1.55v.

IMO load temps should never go above 55. 56-61 is considered safe but may cause stability issues. 62+ is dangerous.